In many applications, a light source and a detector are used to analyze an object of interest. With reference to FIG. 1, a housing 103 carries a light source 105 and a detector 120 and is positioned adjacent a first support element 115 (such as a glass plate). The light source 105 generates a light beam that strikes a portion of an object 110 carried by the first support element 115, and the detector 120 is positioned so that its focal point intersects the light beam at the object 110. As described in U.S. Pat. No. 5,360,523, such an analyzer can be used in DNA sequencing applications. In such an application, a plurality of DNA channels in a gel electrophoresis slab sandwiched between two glass plates are scanned with a laser that excites fluorescent markers attached to DNA strands, and a sensor is focused on the area of the gel slab excited by the laser.
When the thickness of the first support element 115 varies or when a second support element 125 (such as a cover slip or tray, see FIG. 2) is interposed between the object 110 and the first support element 115, the focal point of the detector may no longer be on the object 110. To maintain the focal point on the object 110, the housing 103 carrying the light source 105 and detector 120 can be linearly translated closer to the first support element 115, as shown in FIG. 2. While the focal point of the detector 120 is once again on the object 110, the focal point no longer intersects the light beam. This misalignment can result in a suboptimal analysis of the object 110 (e.g., a faded image or a magnitude response error). Accordingly, unless the object 110 is on the first support element 115, the light beam and the focal point do not coincide.
There is a need, therefore, for an apparatus and method for intersecting a light beam and a focal point of a detector at an object of interest that will overcome the disadvantages described above.
The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims.
By way of introduction, the preferred embodiments described below provide an apparatus and method for intersecting a light beam and a focal point of a detector at an object of interest. In one preferred embodiment, an apparatus is provided comprising a first support element and a first member carrying a light source and a detector. The first member is pivotable between first and second positions, and when the first member is in the first position, a light beam generated by the light source and a focal point of the detector intersect at an object of interest carried by the first support element. When the first member is in the second position, the light beam and the focal point of the detector intersect at an object of interest carried by a second support element disposed on the first support element.
The preferred embodiments will now be described with reference to the attached drawings.